


thursday afternoon

by slotumn



Series: Lysiclaude pseudo-incest [1]
Category: Fire Emblem: Fuukasetsugetsu | Fire Emblem: Three Houses
Genre: Alternate Universe - Foster Family, Alternate Universe - Modern Setting, Angst and Porn, Brother/Sister Incest, Condoms, F/M, First Time, Foster Care, Loss of Virginity, Painful Sex, Porn with Feelings, Pseudo-Incest, Separation Anxiety, Sort Of, Stomach Bulge, Vaginal Sex, and theyre incesty too but it doesnt come up in the fic, but it gets better, claude has issues, there are also twin byleths, they run the foster home
Language: English
Status: Completed
Published: 2021-01-03
Updated: 2021-01-03
Packaged: 2021-03-12 17:40:33
Rating: Explicit
Warnings: Underage
Chapters: 1
Words: 1,848
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/28514346
Author URL: https://archiveofourown.org/users/slotumn/pseuds/slotumn
Summary: He wished turning her down was as easy as, "We can't, we're related."
Relationships: Lysithea von Ordelia/Claude von Riegan
Series: Lysiclaude pseudo-incest [1]
Series URL: https://archiveofourown.org/series/2088765
Kudos: 13





	thursday afternoon

**Author's Note:**

> By the decree of people on Twitter, my first "full length" fic of the year is pseudo-incest brosis Lysiclaude. Here's to another year of me dumping all my personal tastes onto these two!

He wished turning her down was as easy as, "We can't, we're related."

The two of them were very much _not_ related, as anyone could tell from a glance, and legally, they were strangers who just happened to have ended up at the same foster home. 

It was unfair, he thought. They were more brother and sister than the people he shared a father with— the people he ran away from. 

If only their bond meant something to the rest of the world.

If only it meant something to _himself_ , when she climbed onto his lap and kissed him with her soft, soft lips. 

* * *

Sometimes, the only form of intimidation people needed were their own imaginations.

The exact information others were given was "Claude von Riegan put himself into foster care," but of course they didn't leave it at just that; the rumor mill spun all sorts of speculations into widely-accepted factoids— something about how he stabbed his own parents, joined a gang, and did time in juvenile detention. 

He didn't bother correcting it. Warding off the worst people in school from Lysithea, just by being close to her, was more than worth the dirty looks. Their actual schedules rarely overlapped, though, since she was a freshman and he was a senior, and extracurricular activities kept her busy most days of the week. 

But today was Thursday.

"The others aren't here yet."

Classes ended an hour earlier than usual, neither of them had clubs to attend, and they'd have the house to themselves until one of the other kids came home, or until Leth and Zev did. 

"Yeah, so now would be the perfect time for you to tune into Toon Channel in the living room," Claude joked. 

"What would I watch Toon Channel for?"

"You're not gonna catch up on the latest season of Definite Spectacle Archipelago?" 

Lysithea winced, upon being reminded of her brief preteen obsession. 

"That thing's still going?"

"Mhm."

"The plot completely fell off after first season, anyway," she muttered, then tugged on his sleeves. "Let's go to your room."

"For what?"

His room wasn't just his room, as it was a group home; he shared it with Raphael and Ignatz, and previously Lorenz, until the latter moved out for college. 

It wasn't that he didn't trust those two, but the less anyone knew, the better.

"Let's go."

As usual, she didn't give him an option. 

* * *

"Can't you guys keep this place clean for _one_ week?"

Claude used his feet to nudge a dumbbell out of the way. "Hey, you try being roommates with these two."

Sketchbooks, clothes, books, and gym equipments strewn everywhere— it wasn't exactly the place the romantic in him wanted to bring a girl to, but Lysithea wasn't just a girl, was she?

She was his sister, so the whole point was that she could see these things and call him stupid and annoying and—

"Claude. Here."

—they were kissing, again, even though he swore he'd sit her down and tell her this had to stop.

She was kissing him, on his bed, tongue giving little kittens licks on his lower lip, and his stupid teenage dick was getting hard, _again_. 

The first time it happened, he had the sense to stop before it could go any further, but Lysithea kept coming back. She didn't give up until he touched her, first over her clothes, then under them, then until she came, hips grinding and pressing her little clit against his fingers as she suppressed her own moans into a pillow.

He never let her touch him in return, of course. 

As long as it was strictly focused on her, he could _almost_ justify it as simply "helping." "Exploring your sexuality is a normal part of puberty and teenhood," blah blah blah, and if she needed a hand with it (literally), it shouldn't be anyone other than her brother's, thought the master self-justifier in him. 

But the moment he got off, he'd be using her for his own ends, like he did with everyone else, and then their relationship wouldn't be _special_ anymore. 

He couldn't be her unconditionally loving, unconditionally protective big brother anymore, and that was why he had to push her hands away from his waistband and say, 

"Can't."

Avoiding pregnancy was an excuse she had to accept; Lysithea was an ambitious girl with a bright future, and even if she were to get an abortion, the early stages of pregnancy would still be difficult on her already frail body. 

This time, though, she didn't back off, and instead took out a square foil.

"It's fine if we have this," she stated, almost matter-of-factly, save for the slight tremble at the beginning. 

He read the label on the packet. "Where did you get it?"

The brand wasn't the one they had in the nurse's or guidance counselor's office, and he doubted that she went and bought it herself, with how easily embarassed she got despite her insistence she was mature. 

"From a friend."

Probably one of the friends she cited as a counterexample, when he tried to say she was too young. (He figured he should be grateful that they used protection, at least.)

"...Lysithea—"

Blood relation (or lack thereof), age, pregnancy risk. 

He was out of excuses, and the only thing left in its place was the fact his cock was aching at the sight of his little sister shimmying out of her underwear while holding the condom between her lips, of her tearing the packet open and clumsily trying to slide it on. 

"Let me do it." 

Lysithea still held onto the base of his cock as he rolled the condom down; there was a little bit of space between her thumb and index fingers, her hand too small to wrap around completely. Then, once it was secure, she lifted her hips and placed the head against her entrance— feeling so warm and tight, even through the layer of latex.

"You shouldn't— not right away," Claude muttered through clenched teeth.

"We don't have _time_ ," she hissed, rubbing back and forth against his cock until a groan escaped him. "Have to finish and clean up before the others get home—"

Then her hips came _down_ , enveloping him so suddenly that he momentarily saw stars. 

But this wasn't about him— Lysithea was whimpering in pain, eyebrows scrunched together and lips stretched in a grimace, and fuck, there was a bit of blood at the base, he had to do something about it—

"Told you to wait," he whispered, after parting from a kiss.

"I'm _fine,_ " she insisted, eyes clenched shut and teary.

Claude sighed and reached down, gently rubbing circles on her clit. Too late to prepare her properly now, but surely it would get slightly better once she came. 

His precious _little sister_ , her slight frame, coming with his cock deep inside of her. 

"Ah..."

The realization, the gravity of what just happened was starting to hit, but he couldn't stop, not when her face was starting to relax, with one hand on his forearm and the other on her own bulging lower belly.

"Feel better now?" he asked, wiping the corner of her eyes. 

"I-I don't know," came a hoarse reply. "K-keep going."

She squeezed even tighter when she came, opening her eyes halfway to look at him with that gaze— looking at him as though he was the only thing in this entire world.

 _Shouldn't be doing this, shouldn't have gotten this far,_ he thought, hugging her and laying her onto the bed. _Should stop now._

And he would have done exactly that, but Lysithea's legs wrapped around his waist the moment he almost pulled out entirely, moaning,

" _Dadash_."

It wasn't his fault that he hadn't heard anyone call him that in so long, much less with that kind of affection behind it. 

Wasn't his fault every single one of his resolutions _shattered_ , right at that moment.

Between doing the right thing and giving his little sister what she wanted, it was always going to be the latter, he realized, breath audibly hitching. 

How foolish, that he ever thoght it could be otherwise.

So he thrusted back in, kissing her instead of trying to say things that would come out jumbled and incoherent anyway.

 _And besides_ , he thought, admiring her skin flushing all over as he sped up, her tiny breasts barely bouncing with each slam in.

Sex was just another way to show love, so this was natural, wasn't it?

He was the weird one, for thinking fucking his sister would destroy their relationship, for thinking their bond was so fragile that something this _good_ would take out what was special about it. 

Yes, that had to be it, he decided, as her back arched, the bulge in her belly even more prominent from the new angle.

Nothing else mattered in the moment but the two of them, and everything he did under these awful circumstances, the good and the bad and the ugly, was to ensure this could last forever. 

_That_ was the answer.

" _Khalid_ — promise me you'll always," Lysithea gasped, tightening around him as another climax began, "promise— that you're always going to be my big brother—"

She reached out and grasped his hand with a weak but determined grip, like a child clinging onto their protector. 

"P-promise me that we're— still family, even after you leave this place—"

After he left. 

After he became an adult— the thing she so desperately wanted to be— and any commonality between them disappeared in the eyes of the law, after the point in his life where he was supposed to walk away from all this and become a person of his own, even though everything that made him who he was lay _right here_.

There was no other way to respond but, 

"Of course we will be, Lyssie— I promise, my sister, _âbji_ —" 

and groans and endless kisses as he came, his heart feeling as though it would burst apart if he loved her any more.

* * *

They did manage to clean up before everyone else got home; it didn't leave much time to enjoy the afterglow, but they did shower together, whispering to each other about the future like the mirrors and walls had ears.

It was almost scary, how he didn't feel any guilt about what they did despite his previous reservations, how a spark ran up his spine when they sat down at dinner like nothing happened and Lysithea had a slight limp only he noticed.

Neither of them spoke of it out loud for rest of the evening. 

But late into the night— long past what Lysithea's (and honestly, his own) bedtime should have been— a message popped up on his phone.

_In case you don't already know, they're all going to be gone from morning to early afternoon this Saturday_   
_My room?_

Claude chuckled to himself, softly as to not wake the other two, and texted back,

_your room._

That night, he dreamt of his little sister's lips, soft and sweet and more special than anything else in the world. 

**Author's Note:**

> Check out the [Lysiclaude NSFW Bingo](https://twitter.com/lysiclaudensfw?s=09)!  
>   
> [Join the Lysiclaude Discord!](https://discord.gg/GZmtGbw)  
>   
> [My twitter](https://twitter.com/slotumn?s=09)  
> 


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